Process for producing a non-wettable amorphous carbon coating on a component

Abstract

A process for producing a coating on components having peripheries to be placed in direct contact with vaporous media. Such peripheries are wetted over part or all of their surface with a film of liquid when the vaporous media are changed from the vapor state into the liquid state by phase transition. Such films of liquid increase the thermal resistance, for example, of the components. In order to avoid such wetting, the peripheries of each component are roughened. A coat of a non-wettable, amorphous carbon is then applied to the peripheries, at least in regions thereof.

We claim:  
     
       1. In a process for producing a coating on components having peripheries to be brought into direct contact with at least one of vapor and condensate of a medium, the improvement which comprises: 
       roughening the peripheries of the components to a depth of up to 20 μm;  
       applying to the peripheries a coat up to 5 μm thick of a non-wettable, amorphous carbon with a formula: a-C:H:X, where X is a chemical element selected from the group consisting of fluorine and silicon, to produce coated surfaces having uncoated regions and regions coated with the non-wettable, amorphous carbon; and  
       then smoothing the coated surfaces to produce an overall surface area of the uncoated regions being less than 50% of an overall surface area of the regions coated with the non-wettable, amorphous carbon.  
     
     
       2. The method according to  claim 1 , wherein said uncoated regions are surrounded by said coated regions. 
     
     
       3. The method according to  claim 1 , wherein at least one of said uncoated regions and at least one of said coated regions are on one of said surfaces. 
     
     
       4. In a process for producing a coating on components having peripheries to be brought into direct contact with at least one of vapor and condensate of a medium, the improvement which comprises: 
       roughening the peripheries of each of the components to a depth of between 0.1 mm and 2 mm; and  
       applying to the peripheries a 3 mm to 5 mm thick coat of a non-wettable, amorphous carbon with a structural formula: a-C:H:X, where X is a chemical element selected from the group consisting of fluorine and silicon to produce coated peripheries having uncoated regions and regions coated with the non-wettable, amorphous carbon.